MBtile or Kap missing or hidden?: Zoom into the area of the tiles, they will appear. MBtiles and Kaps only show at certain scales, similar to charts. (You can also make mbtiles at different scales similar to charts).
Navigational KAPS are navigational files in a MapMedia format that is usable by most navigation programs, like OpenCPN or MaxSea or Capt'n Navigator. These files have been made from Google Earth, typically at 7,200 feet (2200m) elevation, to get all the detail possible. Jon Hacking.